A resectoscope is employed transurethrally to perform prostate and/or bladder surgery. This device has an elongate central working section provided with an outer sheath, usually made of stainless steel, which is inserted into the urethra. The outer sheath prevents the urethra from collapsing, while the working elements internally of the sheath are employed to cut away the desired tissue.
Until recently the treatment of benign prostate hyperplasia has been by use of a technique called transurethral resection of the prostate (TURP) utilizing conventional resectoscopes. Such resectoscopes for the most part either are of the cold punch type, wherein the cutting element is unheated, or are of the heated type, where the cutting element, in the form of a conductive wire, is heated through an electrical connection to a diathermy unit. The diathermy unit can be controlled by the surgeon, either through the use of a hand-operated switch or through the use of a foot-operated switch.
In a manually operated resectoscope of the type employing a heated cutting element, the surgeon manually extends the cutting element beyond the end of the outer sheath to a position engaging the tissue to be cut. Thereafter, the cutting element is energized through actuation of the diathermy unit, and at the same time the cutting element is manually retracted to cause it to slice away a desired amount of the tissue. The surgeon views the area being operated upon through a telescopic system that also is mounted within the stainless steel sheath of the device, and a continuous irrigation system is utilized to keep the line-of-sight free of blood and other debris.
During prostate surgery it is common to cut away approximately 1/10 of a gram of tissue with each cutting stroke of the resectoscope. Although the total weight of tissue to be removed varies with the size of the individual and the severity of the problem, it is quite common to remove anywhere from 20 to 150 grams of tissue in a typical prostate operation. Therefore, in even the simplest of operations, it is generally necessary to reciprocate the cutting element at least 200 times.
During transurethral resection of the prostate, fluids are used to irrigate the operative situs during the operation as well as during the immediate postoperative period. The fluid irrigation during the resection has two purposes: to first clarify the area so that the operator's vision is unobstructed and second to remove any prostatic chips toward the bladder. Therefore, the bladder acts as a temporary reservoir for prostatic chips and blood clots. Before the procedure is completed, and sometimes in the middle of the procedure, the bladder must be irrigated and cleared completely of any prostatic chips or clots. It would, however, facilitate the operation if irrigation fluid and the prostatic chips or clots could be removed without having to irrigate the bladder.
In the diathermy unit previously discussed, electricity is used both for cutting and coagulation. The electricity runs through a hot metal were (isolated in the proximal part) to cut pieces or chips of the prostate and to coagulate any bleeding areas. The use of these electrically operated resectoscopes has certain disadvantages. For example, there is a need for a very powerful diathermy machine; the electric loops through which the electricity runs have an average useful life of only one or two patients; each loop costs approximately fifty dollars; and the procedure produces tissue charring or carbonization which produces a slightly higher risk of a location for infection. (Charred tissue is dead tissue and with urine and blood flows close thereto, bacteria might find a suitable place to multiply.)
Furthermore, while operating time depends greatly on the size of the prostate as well as the skill of the operator, other considerations also increase operating time. These include excessive bleeding, a small bladder capacity to receive the irrigation fluid and the removal of prostatic chips. The average skilled operator or surgeon may take approximately one minute to remove each gram of prostatic tissue. Since the majority of prostate surgical removals are under 100 grams, e.g., approximately 20 to 60 grams, it can be seen that the process can become quite time consuming--and there are some prostates that range in size from 100 to 250 grams. Accordingly, it can be seen that any process or apparatus which decreases the operating time would be very beneficial.
In U.S. Pat. No. 4,955,882 (Hakky) there is disclosed a resectoscope instrument embodying a laser for use in coagulating and removing prostate tissue. A cutting blade is provided in that instrument for cutting away tissue which had been coagulated by the laser. To that end the instrument utilizes a forward directed laser to penetrate the tissue to be removed prior to cutting of that tissue. The instrument also includes means by which a irrigation fluid can be continuously supplied to and removed from the cutting site, so that the irrigation fluid, cut tissue and any debris are withdrawn through the instrument without the need to fully irrigate the bladder.
Some devices are now becoming available for effecting transurethral resection of the prostate by means of a laser. For example, Surgical Laser Technologies of Oaks PA offers a "contact laser" which serves to vaporize the prostate in order to reduce bleeding and morbidity common with the traditional transurethral resection techniques. Another laser device is offered by Intra-Sonix, Inc. of Burlington, Mass. for effecting what it refers to as "transurethral ultrasound guided laser induced prostatectomy" (TULIP). That device utilizes a laser mounted on an ultrasonic transducer introduced transurethrally to heat the prostate tissue to the point that it becomes necrotic so that it sloughs off and is expelled in the patient's urine over an extended period of time, e.g., three to six weeks, following the surgical procedure.
As should be appreciated by those skilled in the art, when performing a prostate resection (or other tissue resection procedures, for that matter) it is desirable to be able to be able to retrieve the removed tissue for analysis, e.g., histological examination. Thus, laser devices which do not include any means for effecting the retrieval of lased tissue, particularly with the cellular architecture of that tissue substantially preserved, leave much to be desired from the standpoint of patient care. For example, the use of such devices leaves open the possibility of the failure to detect pathological conditions, e.g., malignant cells, in the removed tissue. Accordingly, the need exists for a laser resectoscope for effecting transurethral prostatectomy or other surgical procedures which addresses this concern.
A further consideration of prostate surgery is the fact that the capsule of the prostate contains many veins, and if any of these are breached, the capsule will bleed profusely and will allow the irrigation fluid to escape outside the urinary system into the area surrounding the prostate. This not only causes pain, but electrolyte disturbance with an increased morbidity and even possibly mortality. In order to avoid piercing the capsule, many surgeons stop short of the capsule by 0.5-1 mm or more depending on the skill of the operator and anatomy of the prostate. It would, of course, be beneficial to get as close to (without invading the capsule) as possible. Such skill is only obtained after many years of practice.
Thus, a need also exists for apparatus to enable the performance of prostate surgery as close to the capsule or even up to the capsule without damaging the capsule. Having such ability would not only allow much more thorough removal of the undesirable tissue, but would also reduce the anxieties associated with possible invasion of the capsule.